Piston spreader



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flrroEn/EX May 30, 1939. c. A. MARIEN PISTON SPREADER Filed June 22, 1936 Patented May 30, 1939 UNITED STATES PATENT OFFICE PISTON SPREADER Application June 22, 1936, Serial No. 86,505

1 Claim.

My invention has relation to improvements in devices for spreading the pistons of internal combustion engines in order to restore them to proper shape after they have become distorted through prolonged use. The invention consists in the novel features of construction more fully set forth in the specification and pointed out in r the claim. a

It is a matter of general knowledge, among those conversant with the art to which the invention relates, that alloy pistons having a longitudinally slotted skirt will eventually collapse under the strain of continued use. This collapse occurs particularly in the vicinity of the lower part of the skirt and introduces excessive clearances in the cylinder of the engine, permitting what is known in the trade as oil pumping and loss of compression. Obviously, the eificiency of the engine is very greatly impaired and some way must be found to repair the pistons or insert new pistons into the cylinders. In the last few years spring elements of various construction have been inserted within the pistons for the purpose of restoring the skirt thereof to its proper shape and size and these devices, generally known as piston expanders, have been very satisfactory where the distortion or collapse of the piston skirt has not been excessive. However, in the case of pistons which have become distorted to a very high degree, there is not sufficient inherent tension in the piston expander to bring the piston skirt back to its normal shape. Nor would it be desirable to have a piston expander with such great tension that it would restore the shape of the piston skirt as this would cause the piston to fit so tightly against the cylinder wall as to introduce excessive friction in the cylinder.

The purpose of the present invention is to spread a distorted piston skirt to approximately its original shape, after which the device, which I term a piston spreader, is removed from the piston and a piston skirt expander of any desirable type inserted in the skirt to maintain the same in normal condition and prevent a recurrence of a collapse thereof.

In the present invention I am concerned only with the spreading of the skirt preparatory to the insertion of an expander. It is therefore the principal object of the invention to provide a piston spreader that is insertable within the piston and that embodies movable elements which may be moved outwardly to exert the necessary force on the piston skirt to enlarge and restore the same to its proper size.

It is a further object to provide a piston spreader that is adaptable to diiferent sizes of pistons, within a limited range, so that a different spreader will not have to beprovided for every size of piston.

It is also the object of the invention to provide a piston spreader that is comparatively simple and that may be easily and quickly operated.

Further and other advantages will be better apparent from a detailed description of the invention in connection with the accompanying drawing, in which:

Figure 1 is a combined side elevation and middle longitudinal section through a piston showing my improved piston spreader applied thereto, part of the spreader being broken away; Fig. 2 is a combined end view and section taken on the line 2--2 of Fig. 1 showing the piston and spreader applied thereto; and Fig. 3 is a detached side elevational view of my improved spreader.

Referring to the drawing, and for the present to Figs. 1 to 3, inclusive, P represents an alloy piston of a common type provided with oppositely disposed transverse slots s, s at the closed ends of a piston skirt S and a longitudinal slot 8. My improved piston spreader comprises a pair of oppositely disposed shoes I, I adapted for engagement with the wall of the piston skirt S, said shoes being connected by a pair of toggle links 2, 2. The shoes I, I are formed of metal stampings of U-shaped cross section and the sides I, I of each shoe are traversed about midway their sides by a rivet 3 which also traverses the ends of toggle 2 and serves as a pivot therefor. The toggles 2, 2 are also of U-shaped cross section, except at their extremities, and have their inner ends in overlapping relation and pivotly connected by means of a rivet 4 to the inner end of a bolt 5, the outer end of which bolt is provided with screw threads 6.

The threaded extremity 6 of the bolt 5 passes through an opening 0' in a boss or abutment 'I centrally formed in an arcuate beam 8 which is also of U-shaped cross section. The top wall 9 of the beam is bent inwardly to provide bottom plates I0, I8 a short distance above the ends of the side walls II, II of the member 8. breadth of the member 8 (that is the distance between side walls II, II) is slightly more than the breadth of the shoes I, I so that the shoes may enter between the side walls II II in the extremities of the member 8 and bear against the bottom plates III, III (Fig. 1). A nut 12 is screwed over the extremity 6 of the bolt 5 for the purpose of drawing the bolt 5 upwardly through the boss I when it is desired to increase the angle be- The tween the toggle links 2, 2 for the purpose of forcing the shoes I further about to effect a spreading of the skirt S of the piston P.

It is apparent that before inserting the piston spreader into a piston, the nut I2 is withdrawn from the bolt 5 so as to permit the links 2,2 to fold somewhat together and draw the shoes I, I

inwardly in order that the device may be easily inserted into the piston skirt. After the device has been inserted in the proper location in the skirt, the nut I2 is turned so as to draw the bolt 5 outwardly to straighten the toggle and" spread the shoes I, I the required amount tore 'store the proper size to the piston skirt. The

piston may now be heat treatedwith thepiston' spreader in p1ace so as to permanently setthe' skirt in its restored size.

After a piston has been spread to the' proper' gle links connected between the shoes, and a I drawb'olt'between the toggle links and the abutment member whereby, upon drawing up the bolt, theabutment member and the shoes will be heldin intimate'engagement while the shoes are spread apart simultaneously therewith.

CHARLES A. M'ARIEN. 

